1. Technical Field
The present invention relates to a driving method of an electrophoretic display device.
2. Related Art
An electrophoretic display device includes a plurality of first electrodes (pixel electrodes), a second electrode facing the plurality of first electrodes, and electrophoretic elements interposed between the electrodes. To display an image by the electrophoretic display device, image signals are supplied to memory circuits via switching elements and stored in the memory circuits first. The image signals stored in the memory circuits are input to the first electrodes, and a potential difference occurs between each of the first electrodes and the second electrode applied with a predetermined potential when a potential is applied to the first electrodes.
JP-A-2003-84314 disclosed a structure of the memory circuit. The memory circuit may be an SRAM type using static random access memories (SRAMs) or a dynamic random access type (DRAM type) DRAM type using condensers.
When displaying an image by an electrophoretic display device, a sufficient potential difference must be given to the electrodes interposing the electrophoretic element therebetween so that electrophoretic particles can migrate to either one electrode of the first electrode or the second electrode. Accordingly, a power source voltage of the memory circuit must be 10V or higher. At this time, in the case in which neighboring pixels display different colors, the first electrodes (pixel electrodes) of the neighboring pixels are applied with different potentials from each other.
Accordingly, there is a large potential difference between the potentials applied to the first electrodes of the neighboring pixels, and therefore there is the possibility that a leak current flows across the neighboring first pixels via an adhesive used for fixing the electrophoretic elements to a substrate. Although the leak current for only a single pixel is small, the total leak current of the entire electrophoretic display device is very large, resulting in the increase of power consumption.
Further, there is the possibility that the first electrodes cause chemical reactions by the leak current, which is likely to result in deterioration of reliability as the electrophoretic display device. For example, a material, such as platinum which is chemically stable and has the high anti-erosion property is used as the first electrodes to improve the reliability. However, such a method brings about a problem with the increase of manufacturing cost.
As means for solving the above-mentioned problems, JP-A-2007-087666 discloses an electrophoretic display device in which a potential of the pixel electrode can be controlled by a switching circuit. According to this electrophoretic display device, it is possible to suppress the leak current and can control a display by using a control line.